Home Home > GIT Browse
summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorEric Biggers <ebiggers@google.com>2017-10-09 12:51:27 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-11-02 09:36:48 +0100
commit5560a1cac11138fe3df5643c7819fd3c0d3755eb (patch)
tree6954583d4063db7aee8b8d931cdedc9921d27d87
parent56621bc7d28c8023c020f0f38b5cf808f46ee5f9 (diff)
ecryptfs: fix dereference of NULL user_key_payload
commit f66665c09ab489a11ca490d6a82df57cfc1bea3e upstream. In eCryptfs, we failed to verify that the authentication token keys are not revoked before dereferencing their payloads, which is problematic because the payload of a revoked key is NULL. request_key() *does* skip revoked keys, but there is still a window where the key can be revoked before we acquire the key semaphore. Fix it by updating ecryptfs_get_key_payload_data() to return -EKEYREVOKED if the key payload is NULL. For completeness we check this for "encrypted" keys as well as "user" keys, although encrypted keys cannot be revoked currently. Alternatively we could use key_validate(), but since we'll also need to fix ecryptfs_get_key_payload_data() to validate the payload length, it seems appropriate to just check the payload pointer. Fixes: 237fead61998 ("[PATCH] ecryptfs: fs/Makefile and fs/Kconfig") Reviewed-by: James Morris <james.l.morris@oracle.com> Cc: Michael Halcrow <mhalcrow@google.com> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/ecryptfs/ecryptfs_kernel.h25
-rw-r--r--fs/ecryptfs/keystore.c9
2 files changed, 25 insertions, 9 deletions
diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index 90d1882b306f..4682bef34bb6 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -84,11 +84,16 @@ struct ecryptfs_page_crypt_context {
static inline struct ecryptfs_auth_tok *
ecryptfs_get_encrypted_key_payload_data(struct key *key)
{
- if (key->type == &key_type_encrypted)
- return (struct ecryptfs_auth_tok *)
- (&((struct encrypted_key_payload *)key->payload.data)->payload_data);
- else
+ struct encrypted_key_payload *payload;
+
+ if (key->type != &key_type_encrypted)
return NULL;
+
+ payload = key->payload.data;
+ if (!payload)
+ return ERR_PTR(-EKEYREVOKED);
+
+ return (struct ecryptfs_auth_tok *)payload->payload_data;
}
static inline struct key *ecryptfs_get_encrypted_key(char *sig)
@@ -114,13 +119,17 @@ static inline struct ecryptfs_auth_tok *
ecryptfs_get_key_payload_data(struct key *key)
{
struct ecryptfs_auth_tok *auth_tok;
+ struct user_key_payload *ukp;
auth_tok = ecryptfs_get_encrypted_key_payload_data(key);
- if (!auth_tok)
- return (struct ecryptfs_auth_tok *)
- (((struct user_key_payload *)key->payload.data)->data);
- else
+ if (auth_tok)
return auth_tok;
+
+ ukp = key->payload.data;
+ if (!ukp)
+ return ERR_PTR(-EKEYREVOKED);
+
+ return (struct ecryptfs_auth_tok *)ukp->data;
}
#define ECRYPTFS_MAX_KEYSET_SIZE 1024
diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c
index 635e8e16a5b7..5924e279733f 100644
--- a/fs/ecryptfs/keystore.c
+++ b/fs/ecryptfs/keystore.c
@@ -458,7 +458,8 @@ out:
* @auth_tok_key: key containing the authentication token
* @auth_tok: authentication token
*
- * Returns zero on valid auth tok; -EINVAL otherwise
+ * Returns zero on valid auth tok; -EINVAL if the payload is invalid; or
+ * -EKEYREVOKED if the key was revoked before we acquired its semaphore.
*/
static int
ecryptfs_verify_auth_tok_from_key(struct key *auth_tok_key,
@@ -467,6 +468,12 @@ ecryptfs_verify_auth_tok_from_key(struct key *auth_tok_key,
int rc = 0;
(*auth_tok) = ecryptfs_get_key_payload_data(auth_tok_key);
+ if (IS_ERR(*auth_tok)) {
+ rc = PTR_ERR(*auth_tok);
+ *auth_tok = NULL;
+ goto out;
+ }
+
if (ecryptfs_verify_version((*auth_tok)->version)) {
printk(KERN_ERR "Data structure version mismatch. Userspace "
"tools must match eCryptfs kernel module with major "